1. Technical Field
The present invention relates to polarization mode dispersion compensation systems and methods and more particularly to an equalization system and method employing a BCJR (Bahl, Cocke, Jelinek and Raviv) based equalizer (hereinafter BCJR equalizer) and a novel class of low-density parity-check (LDPC) codes.
2. Description of the Related Art
At high transmission rates, e.g., at 40 Gb/s and beyond, the signal quality of the wavelength division multiplexed (WDM) optical channels is degraded significantly due to polarization-mode dispersion (PMD). The signal quality of the wavelength division multiplexed (WDM) optical channels is degraded significantly due to linear and non-linear effects, in particular fiber nonlinearities and polarization-mode dispersion (PMD). In contrast to chromatic dispersion impairments, the PMD is time variant and stochastic in nature, making the PMD compensation more challenging.
Since the electrical PMD compensators rely on fast electronic signal processing with potential to be implemented as low-cost integrated devices, greater attention is being applied to different electronic PMD equalization techniques. For example, turbo equalization based on convolutional codes, has been considered for PMD compensation. Unfortunately, the turbo equalization scheme based on convolutional codes exhibits the error floor phenomena at bit-error ratios (BERs) of about 10−6.